Pain and Analgesics

Question 1

What is pain?

Answer 1

The subjective conscious appreciation of a stimulus causing or threatening tissue damage.

Question 2

What is nociception?

Answer 2

Th physical process of detecting and transmitting noxious stimuli.

Question 3

What are nociceptors?

Answer 3

Sensory receptors that detect noxious stimuli, often located in free nerve endings.

Question 4

What are the two types of nociceptive fibres?

Answer 4

Aδ fibers (sharp pain) and C fibers (dull, aching pain).

Question 5

What receptor is activated by heat, protons, and capsaicin in nociceptors?

Answer 5

TRPV-1 (Vanilloid receptor 1)

Question 6

What is hyperalgesia?

Answer 6

An increased response to a noxious stimulus.

Question 7

What is allodynia?

Answer 7

A painful response to a normally non-noxious stimulus.

Question 8

What neurotransmitters are involved in nociceptive transmission at the spinal level?

Answer 8

Glutamate, Substance P, and CGRP (Calcitonin Gene-Related Peptide).

Question 9

What are AMPA and NMDA receptors?

Answer 9

Glutamate receptors involved in fast (AMPA) and slow (NMDA) excitatory postsynaptic potentials (EPSPs).

Question 10

What is the “wind-up” phenomenon in pain?

Answer 10

Repeated stimulation of nociceptors causing increased spinal neuron excitability, leading to central sensitisation.

Question 11

What are the primary endogenous opioids?

Answer 11

Endorphins, enkephalins, and dynorphins.

Question 12

What are the three main opioid receptros?

Answer 12

μ (mu), κ (kappa), and δ (delta)

Question 13

What are the effects of μ-opioid receptor activation?

Answer 13

Analgesia, euphoria, respiratory depression and constipation.

Question 14

How do NSAIDs reduce pain?

Answer 14

By inhibiting cyclooxygenase (COX) enzymes, decreasing prostaglandin synthesis.

Question 15

What are COX-1 and COX-2 enzymes?

Answer 15

COX-1 is involved in protective functions (e.g. gastric mucosa), while COX-2 is induced during inflammation.

Question 16

What is neuropathic pain?

Answer 16

Pain arising from nerve damage or dysfunction, often unresponsive to opioids/NSAIDs.

Question 17

What drugs are used for neuropathic pain?

Answer 17

Tricyclic antidepressants, antiepileptic drugs (e.g., gabapentin), and topical capsaicin

Question 18

What is the WHO pain ladder?

Answer 18

A framework for pain management:
- Mild pain: NSAIDs.
- Moderate pain: Weak opioids (e.g., codeine).
Severe pain: Strong opioids (e.g., morphine).

Question 19

What are the major adverse effects of opioids?

Answer 19

Respiratory depression, constipation, tolerance, dependence and sedation

Question 20

What is Substance P?

Answer 20

A neuropeptide involved in transmitting pain signals via NK-1 receptors.

Question 21

What role does the periaqueductal gray (PAG) play in pain modulation?

Answer 21

It is a key site in the descending pain pathway that reduces nociceptive transmission.

Question 22

How do cannabinoids relieve pain?

Answer 22

By acting on cannabinoid receptors to reduce nociceptive signalling.

Question 23

What is central sensitisation?

Answer 23

Increased excitability of spinal neurons, amplifying pain responses.

Question 24

What are common undesirable effects of NSAIDs?

Answer 24

Gastric irritation, kidney disorders and increased cardiovascular risk (with COX-2 inhibitors).